The invention relates to a repellent pest control system.
A subject of the invention is a repellent pest control system for the controlled release of a pest control active ingredient from a polymer matrix which comprises
a vinyl polymer
a liquid plasticizer for said polymer, said plasticizer being present in the maximum amount possible and still maintain a dry and flowable blend of plasticizer and polymer and
triphenyl phosphate, said triphenyl phosphate being present in an amount sufficient to serve as a carrier for said active ingredient.
In particular a subject of the invention is a system wherein the polymer is a vinyl chloride polymer or copolymer, and/or a system wherein the liquid plasticizer is an adipic ester or a phthalic ester, and/or a system wherein the amount of triphenyl phosphate is within the range of about 10 to 35 percent by weight of the total system.
The pest system may be produced as described in the Europeen Patent Application 539295.
As a preferred system, it can be mentioned in a solid polymeric composition for the release of a pest control active ingredient which comprises a vinyl polymer, a liquid plasticize and a pest control active ingredient, the improvement which comprises including triphenyl phosphate in said composition, said triphenyl phosphate being present in an amount sufficient to serve as a carrier for said active ingredient and precisely a composition wherein the amount of triphenyl phosphate is from about 10 to 35 percent by weight of the composition.
A more particular subject of the invention is the system wherein the active ingredient is pyrethroid.
The pyrethroid may be chosen from the following compounds: deltamethrin, acrinathrin, tralomethrin, permethrin, cypermethrin, alphamethrin, cyhalothrin, fenvalerate, cyfluthrin, flucythrin, flucythrinate, fluvalinate, fenpropathrin, bifenthrin, esfenvalerate, alphacypermethrin, betacyfluthrin, lambdacyalothrin, taufluvalinate or silafluofen.
As preferred pyrethroid, it can be mentioned deltamethrin.
The repellent system according to the invention enables external parasites to be combatted; it is applicable, in particular, to the control of acaridae, for example, ticks and scabies, the warble, insects such as lice, bugs and different kinds of biting and stinging flies.
A more particular subject of the invention is a repellent pest control system wherein the pests are phlebotomine sandflies.
Canine leishmaniasis caused by Leishmania infantum is highly prevalent in all countries of the Mediterranean subregion and in many countries of Latin America, notably Brazil. In most foci it is probable that all dogs are bitten by an infected sandfly in the first transmission season. After an incubation period of up to one year, or even more, some dogs develop clinical signs of leishmaniasis and rising titres of antibodies, whereas others mount an effective cell mediated immune response with low or negative titres of antibodies, and no signs of disease. The prevalence rates of serologically positive dogs in the Mediterranean subregion are commonly around 10% but may exceed 30%. In southern Spain, half of the dogs seen by veterinarians have leishmaniasis. Once signs of the disease are apparent, untreated dogs invariably die. Treatment (for example with pentavalent antimonials) is expensive and is almost always followed by a relapse. No vaccines are available.
The importance of canine leishmaniasis as a veterinary problem is overshadowed by the fact that dogs are reservoirs of visceral leishmaniasis for the human population and attempts to control canine leishmaniasis seem always to be aimed at reducing the risk of infection to man rather than dogs. However, with the exception of western,China where canine leishmaniasis and the human disease were eradicated by the destruction of all dogs, the results of control campaigns have been disappointing. As the vectors are not strongly endophagic (feeding indoors) or endophilic (resting indoors), insecticide spraying or houses will not greatly decrease the risk of infection, and expensive campaigns to reduce the reservoir of infection by culling seologically positive dogs have met with owner resistance and only limited success.
Among the proven or suspected vector of canine leishmaniasis in the Mediterranean subregion are Phlebotomus perniciosus (France, Spain, Portugal, Maghreb), P. ariasi (France, Spain, Portugal, Morocco), P. perfiliewi (Italy, Greece, Serbia, Magreb), P. tobbi (Greece, Cyprus, Syria), P. neglectus (Greece), P. syriacus (Syria, Lebanon, Israel) and P. langeroni (Egypt). These closely related flies have a similar biology. The female flies (but not the males) take blood meals from any available mammal, with a preference for canids. They bite at night the highest activity outside. The risk of infection is, therefore, somewhat higher outdoors than indoors.
In Central and South America, the closely related parasite (Leishmania chagasi) is carried by different species of sandflies (principally Lutzomyia longipalpis, but also Lu. evansi in parts of Colombia and Venezuela). As in the Mediterranean subregion, dogs are commonly infected, but the prevalence of the human disease is generally higher, notably in Brazil. The principal vector in the Neotropics is present in enormous numbers in and around houses and feeds on any available mammal or bird. It has a wide distribution and has proved impossible to control.
As a prefered subject of the invention, the repellent pest control system is a dog collar, for example a dog collar comprising 2 to 6 g of deltamethrin per 100 g of collar with an optimum of 4 g of deltamethrin per 100 g of collar.
Another subject of the invention is the protection of dog from bites of phlebotomine sandflies by deltamethrin collar for the control of canine leishmaniasis.
Deltamethrin dog collars protect dogs from almost all the bites of phlebotomine sandflies for a period up to and including 34 weeks. While absolute protection from leishmaniasis cannot be expected, the risk to dogs wearing collars should be reduced to a negligible level compared to dogs without collars. In addition, when confined with collared dogs, a high proportion of flies die within two hours. It is concluded that the collars have strong anti-feeding and lethal effects to phlebotomine sandflies lasting for a complete sandfly season.
The collars could be used in two ways. Firstly, they offer a means for owners to protect their dogs from canine leishmaniasis. secondly, they provide a unique tool in the control of human visceral leishmaniasis with dogs as the main source of infection. Because the collars break the contact between dogs and sandflies, it is probable that their universal use would stop the circulation of the parasite and the human disease would disappear.